/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 */

package org.apache.catalina.tribes.group.interceptors;

import org.apache.catalina.tribes.Channel;
import org.apache.catalina.tribes.ChannelException;
import org.apache.catalina.tribes.ChannelMessage;
import org.apache.catalina.tribes.Member;
import org.apache.catalina.tribes.UniqueId;
import org.apache.catalina.tribes.group.ChannelInterceptorBase;
import org.apache.catalina.tribes.group.InterceptorPayload;
import org.apache.catalina.tribes.transport.bio.util.FastQueue;
import org.apache.catalina.tribes.transport.bio.util.LinkObject;

/**
 * 
 * The message dispatcher is a way to enable asynchronous communication through
 * a channel. The dispatcher will look for the
 * <code>Channel.SEND_OPTIONS_ASYNCHRONOUS</code> flag to be set, if it is, it
 * will queue the message for delivery and immediately return to the sender.
 * 
 * 
 * 
 * @author Filip Hanik
 * @version 1.0
 */
public class MessageDispatchInterceptor extends ChannelInterceptorBase
		implements Runnable {
	protected static org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory
			.getLog(MessageDispatchInterceptor.class);

	protected long maxQueueSize = 1024 * 1024 * 64; // 64MB
	protected FastQueue queue = new FastQueue();
	protected boolean run = false;
	protected Thread msgDispatchThread = null;
	protected long currentSize = 0;
	protected boolean useDeepClone = true;
	protected boolean alwaysSend = true;

	public MessageDispatchInterceptor() {
		setOptionFlag(Channel.SEND_OPTIONS_ASYNCHRONOUS);
	}

	public void sendMessage(Member[] destination, ChannelMessage msg,
			InterceptorPayload payload) throws ChannelException {
		boolean async = (msg.getOptions() & Channel.SEND_OPTIONS_ASYNCHRONOUS) == Channel.SEND_OPTIONS_ASYNCHRONOUS;
		if (async && run) {
			if ((getCurrentSize() + msg.getMessage().getLength()) > maxQueueSize) {
				if (alwaysSend) {
					super.sendMessage(destination, msg, payload);
					return;
				} else {
					throw new ChannelException(
							"Asynchronous queue is full, reached its limit of "
									+ maxQueueSize + " bytes, current:"
									+ getCurrentSize() + " bytes.");
				}// end if
			}// end if
			// add to queue
			if (useDeepClone)
				msg = (ChannelMessage) msg.deepclone();
			if (!addToQueue(msg, destination, payload)) {
				throw new ChannelException(
						"Unable to add the message to the async queue, queue bug?");
			}
			addAndGetCurrentSize(msg.getMessage().getLength());
		} else {
			super.sendMessage(destination, msg, payload);
		}
	}

	public boolean addToQueue(ChannelMessage msg, Member[] destination,
			InterceptorPayload payload) {
		return queue.add(msg, destination, payload);
	}

	public LinkObject removeFromQueue() {
		return queue.remove();
	}

	public void startQueue() {
		msgDispatchThread = new Thread(this);
		msgDispatchThread
				.setName("MessageDispatchInterceptor.MessageDispatchThread");
		msgDispatchThread.setDaemon(true);
		msgDispatchThread.setPriority(Thread.MAX_PRIORITY);
		queue.setEnabled(true);
		run = true;
		msgDispatchThread.start();
	}

	public void stopQueue() {
		run = false;
		msgDispatchThread.interrupt();
		queue.setEnabled(false);
		setAndGetCurrentSize(0);
	}

	public void setOptionFlag(int flag) {
		if (flag != Channel.SEND_OPTIONS_ASYNCHRONOUS)
			log
					.warn("Warning, you are overriding the asynchronous option flag, this will disable the Channel.SEND_OPTIONS_ASYNCHRONOUS that other apps might use.");
		super.setOptionFlag(flag);
	}

	public void setMaxQueueSize(long maxQueueSize) {
		this.maxQueueSize = maxQueueSize;
	}

	public void setUseDeepClone(boolean useDeepClone) {
		this.useDeepClone = useDeepClone;
	}

	public long getMaxQueueSize() {
		return maxQueueSize;
	}

	public boolean getUseDeepClone() {
		return useDeepClone;
	}

	public long getCurrentSize() {
		return currentSize;
	}

	public synchronized long addAndGetCurrentSize(long inc) {
		currentSize += inc;
		return currentSize;
	}

	public synchronized long setAndGetCurrentSize(long value) {
		currentSize = value;
		return value;
	}

	public void start(int svc) throws ChannelException {
		// start the thread
		if (!run) {
			synchronized (this) {
				if (!run && ((svc & Channel.SND_TX_SEQ) == Channel.SND_TX_SEQ)) {// only
																					// start
																					// with
																					// the
																					// sender
					startQueue();
				}// end if
			}// sync
		}// end if
		super.start(svc);
	}

	public void stop(int svc) throws ChannelException {
		// stop the thread
		if (run) {
			synchronized (this) {
				if (run && ((svc & Channel.SND_TX_SEQ) == Channel.SND_TX_SEQ)) {
					stopQueue();
				}// end if
			}// sync
		}// end if

		super.stop(svc);
	}

	public void run() {
		while (run) {
			LinkObject link = removeFromQueue();
			if (link == null)
				continue; // should not happen unless we exceed wait time
			while (link != null && run) {
				link = sendAsyncData(link);
			}// while
		}// while
	}// run

	protected LinkObject sendAsyncData(LinkObject link) {
		ChannelMessage msg = link.data();
		Member[] destination = link.getDestination();
		try {
			super.sendMessage(destination, msg, null);
			try {
				if (link.getHandler() != null)
					link.getHandler().handleCompletion(
							new UniqueId(msg.getUniqueId()));
			} catch (Exception ex) {
				log.error("Unable to report back completed message.", ex);
			}
		} catch (Exception x) {
			ChannelException cx = null;
			if (x instanceof ChannelException)
				cx = (ChannelException) x;
			else
				cx = new ChannelException(x);
			if (log.isDebugEnabled())
				log.debug("Error while processing async message.", x);
			try {
				if (link.getHandler() != null)
					link.getHandler().handleError(cx,
							new UniqueId(msg.getUniqueId()));
			} catch (Exception ex) {
				log.error("Unable to report back error message.", ex);
			}
		} finally {
			addAndGetCurrentSize(-msg.getMessage().getLength());
			link = link.next();
		}// try
		return link;
	}

	public boolean isAlwaysSend() {
		return alwaysSend;
	}

	public void setAlwaysSend(boolean alwaysSend) {
		this.alwaysSend = alwaysSend;
	}

}
